Nuclear inspection team highlights failures at San Onofre

Monday's disclosures focused further attention on a series of alterations to the original equipment design and why the emerging problems went undetected by the manufacturer, plant operator and regulators.

Those alterations include the addition of 400 tubes to each generator and reconfiguring of supports intended to minimize tube wear and vibration.

The plant's four massive generators were designed to qualify as nearly identical equipment and forgo a license amendment that involves a more rigorous technical review.

Friends of the Earth, an international environmental group active on nuclear safety issues, has asserted for months that plant operator Southern California Edison played down the extent of design changes to the generators in order to avoid a license amendment.

On Monday, the group sought standing under federal regulations to petition the Nuclear Regulatory Commission directly.

"Edison made significant design changes without seeking an amendment to its license as required by NRC regulations," said Damon Moglen, climate and energy director for Friends of the Earth. He accused regulators at the same time of being "asleep at the wheel."

Edison has said it was open and transparent with the nuclear commission about changes to the generators.

Nuclear Commission Chairman Gregory Jaczko has said regulators are looking at whether Edison was forthright about the extent of the changes to generators manufactured by Mitsubishi Heavy Industries, and if so whether regulations need to be revised. Collins said it is possible Edison could face penalties stemming from the federal investigation.

The design of the generators is also under congressional scrutiny.

Plant operator Southern California Edison and regulators have not ruled out the possibility that some of the four generators may need to be replaced once again.

The initial replacement cost for the generators was $671 million, a bill shouldered by utility customers across much of Southern California, including San Diego County.

Additional bills for repairs and replacement energy have been accruing since Jan. 31., when a tiny leak of radiation into the atmosphere was traced to a tube leak, shutting down the Unit 3 reactor.

More than 1,300 tubes have been plugged and secured — including many without significant wear — in an effort to contain degradation. Tube-on-tube wear — of particular concern because tubes should never touch — is more pronounced in the southern, Unit 3 reactor.

Edison CEO Ted Craver signaled earlier this month that plans to restart either reactor would not be submitted to the NRC until at least Aug. 1. The company would likely first seek to restart the Unit 2 reactor, which displays less tube wear, while limiting its power output initially in an attempt to moderate tube vibrations.

The Nuclear Regulatory Commission says there is no timetable to restart the reactors.

The extent of the generator-design alterations was described in a January article for Nuclear Engineering International magazine, written by a top-level Edison engineer and a collaborator from Mitsubishi.

That piece, published before the tubing crisis became public, described how the project was configured to meet federal guidelines without triggering a prolonged regulatory review.